There are a number of fields in which improved noninvasive and nondestructive testing and characterization techniques are required. In the field of medicine, various noninvasive testing techniques currently exist, such as ultrasonic scanning and x-rays, which produce images of bone or tissue. Such images are useful for detecting abnormalities in size or shape of an organ, for detecting blockages or other abnormalities in arteries or for detecting fractures in bones. However, such images generally do not reveal chemical or other structural changes in tissue or bone which may be useful in the early diagnosis of various medical problems. For example, a change in bone structure might be indicative of the onset of osteoporosis, while changes in the organization of certain cells within an organ might be an early indication of cancer. Other organ diseases, including those of the heart, lung, liver and kidney, might also result in organizational changes in all or a portion of the affected organ which, if detected, could be used for diagnostic purposes. Further, since a noninvasive procedure such as ultrasonic scanning which does not involve any known risk or substantial discomfort to the patient may be performed at frequent intervals, such a technique could also be utilized to determine the effectiveness of various treatment regimens so that such regimens may be adjusted to meet the needs of the patient.
Similarly, with the aging infastructure in the United States and other countries, aging airline fleets and the like, there is an increasing need for a capability to nondestructively test structures, composite materials and equipment before problems develop. Again, various techniques are currently available which can detect cracks, breaks, bends or similar abnormalities which would turn up when an image of a structure, including hidden structures, is produced. However, problems in such structures can also arise as a result of oxidation, structural fatigue, or other compositional or structural changes which may occur as a result of time, use, shocks or corrosion which might not show up in an image of the structure.